Grit removal apparatus



July 2, 1935. A, pow s 2,906,825

GRIT REMOVAL APPARATUS Original Filed Aug. 23, 1929 3 Sheets-Sheet 1 a T a- 3.4

E A. oowuzs \NVENTOR July 2, I F A DOVVNES 2,006,825

GRIT REMOVAL APPARATUS Original Filed Aug. 23, 1929 s Sheets-Shet 2 F- A. DOWNES NVENTOR y 2, 1935? F. A. DOWNES 2,006,825

GRIT REMOVAL APPARATUS Original Filed Aug. 23, 1929 3 Sheets-$heet 5 I SO I 50 25 52 f 27 4 7 53 a 53 e7 a 7 t 2 22 22 I I0 55 62 52 2 v 65 55 e5 'q' F. A. DOWNES INVENTOR Patented July 2, 1935 fUNlTED STATES PATENT OFFICE GRIT REMOVAL AEPARATUS Application August 23, 1929, Serial No. 387,866

Renewed June 8, 1933 9 Claims. (Cl. 210-3) This invention relates to means for cleaning grit chambers in sewage systems and the like.

It is customary to remove the grit from sewage by passing the sewage simultaneously through a 5 plurality of elongated grit chambers arranged side by side and having theoretically a suiiicient total area and adequate depth so that the rate of flow will permitthe grit to settle out on the bottoms of the grit chambers, which are depressed below the level of the sewer to provide storage pockets in which the grit can build up to a certain point without interrupting the flow of the sewage. For removing the accumulation of grit it is the present practice to cut out one of the chambers by closing its ends, pumping out the liquid sewage and then removing the accumulated grit by means of grab buckets or the like. Obviously this arrangement is not only inconvenient but very unsightly and objectionable, since the grit necessarily contains an abnormal amount of organic solids which settle out as soon as flow through the chamber is stopped. After cleaning the chamber is put into operation and another chamber is closed off and cleaned, so that in a large plant the cleaning process is going on at some point a large part of the time.

When one or more of the grit chambers is cut out,the combined capacity of theremaining grit chambers must be sufficient to accommodate the stream of sewage while leaving the flow and velocity of the flow within the proper limits. Consequently' the number of gritc-hambers is greater than is necessary for use at any onetime and an excessive amount of ground'space orarea is requiredl In the usual form of apparatus there will also be variations in height of accumulated grit which will affect the flow and the velocity of flow of the sewage by changing the; depth of the channels.

The broad object of this invention is to obviate the difficulties set forth by providing an arrangement applicable to the present type of elongated grit chamber which will be adapted to remove settled grit from the chamber bottom without interrupting the flow of sewage, and which may be operated as often as may be required, de-.

pendent upon the rate of deposition of the grit. More specifically, the invention contemplates the provision of a grit collecting unit traveling back and forth over the chamber and provided with a scraper adapted to convey the settled grit to an endof the chamber where suitable removal means is provided and preferably arranged sothat such scraper may be raised into inefiective position during return of the mechanism to the opposite end of the chamber. A further object is to provide a scraper that is yieldably mounted so that when meeting either an abnormal accumulation of grit or an abnormal obstruction it will ride over such obstruction and will penetrate into the accumulated grit only to such a depth as is necessary to provide a maximum load, additional portions of the accumulated grit being moved at each successive reciprocation of the apparatus. Provision is likewise made for automatic electric operation of the cleaning apparatus.

Further objects of the invention are to provide for the general purpose specified apparatus in which the moving parts are in accessible position; apparatus in which the wearing parts are located above the liquid level in the grit chamber; apparatus such as to present minimum obstruction to the flow through the chamber; and apparatus in which the parts entering the liquid have a minimum tendency to collect waste material thereon. 20

Other objects and advantages will be apparent from the following description taken in connection with the accompanying drawings in which Fig. 1 is a vertical sectional view of an illustrative embodiment of the invention, the section being taken on the line l-l of Fig. 2, and certain parts being omitted;

Fig. 2 is a top plan view; and

Fig. 3 is a view in front elevation of the scraper mechanism, the wall of the grit chamber being shown in section on the line 3-3 of Fig. 2.

Referring to the drawings, I0 is a grit chamber having its bottom H below the level of the bottom P2 of the conduit l3 and having at one end a transverse depression or trough 14 serving as a pocket into which the settled material or grit is deposited by means of a scraper including a blade I 5 extending across the chamber and from which such material or grit is withdrawn by suitable means such as a conveyer l6 located therein. The scraper blade I5 is suspended from a carriage H by hangers 18 which are relatively thin transversely of the chamber and therefore present less obstruction to the flow of the material than would otherwise be the case.

The carriage l1 includes a frame H! which is supported at the rear by means of wheels 20 on the ends of a shaft or axle 2| connected with the frame and which wheels rest on rails 22 on the walls of the grit chamber; and at the front by means of wheels 20 resting on 'said rails and fixed on an axle 24 mounted rotatably in bearings 25 on the frame 19 and having fixed thereon a sprocket wheel or sprocket 2B. This sprocket 26 is operatively connected by means of a sprocket chain 21 with a sprocket 28 rotatably mounted on the frame l9 and connected by means of a speed reducer 29 with a reversible motor 30 also mounted on the carriage and controlled by reversing switch 32 on the carriage and connected with the motor by conducting means included in a cable 3|. 4

Electric power is supplied to the switch by means of conductors 33 on the carriage'and electrically connected with conducting means, including a plurality of conductors 34 arranged parallel to the path of the carriage and above the same, by pantograph trolleys including grooved wheels 35 (electrically connected with said conductors) running on said conductors 34 and held yieldably in engagement therewith by means including standards 36 projecting up-' wardly from the carriage l1, and quadrangular frames each consisting of two lower arms 31 pivoted at their lower ends to the upper end of the corresponding standard by spaced pivots 38, and two upper arms 39 pivoted at 40 at their upper ends and supporting the corresponding wheel 35 to turn about the pivotal axis of this connection. Adjacent to their lower ends these'arms 39 are connected respectively with upper and outer ends of the corresponding arms 31 by pivots 4|. The

. arms 39 are also continued below the pivots 4! and at the lower ends of such extensions are connected with the outer ends of helical springs 42 of which the other ends are so connected with the standard 36 by suitable means' such as pins 43, as to press the corresponding wheel 35 against the corresponding conductor 34.

In order to render the scraper blade effective in its movement toward the pocket l4 and ineffective in the opposite or return movement, the upper ends of the hangers 18 are pivotally connected with arms 45 fixed on and' projecting forwardly from a transverse shaft 46 rotatably mounted on the carriage frame I 9. Preferably the upper ends of the hangers l8 are fixed on a shaft 41 and this shaft is rotatably mounted in theiarms 45. Each arm 45 constitutes a part of a bell crank 48 having an upright arm 49 on which is mounted a weight or counterbalance 50 and the extreme or limiting positions of the bellcranks and the associated parts are determined by means including flanges 5| extending inwardly from the outside arms 45 between suitable stop devices, such as dash pots 52 mounted on the frame l9 and having plungers 53 to be engaged by said flanges. a it In order to utilize the scraper blade I 5, the swinging of the. hangers I8 about the axis of the shaft 41 must be controlled and, as here illustrated, this control is effected by means of compressible links 54 pivotally connected at their rear ends with theframe l9 and at their forward ends with the hangers l8. Each of the compressible links includes a forward end member 55, a bar 56 rigidly attached to said member 55 and extending rearwardly therefrom, a rearward end member 51 slidable on said bar, a helical compression spring 58 surrounding said bar and interposed between said members 55 and 51, tie rods 59 passing through flanges at the inner ends of said members 55 and 5I, and nuts 60 threaded on the ends of said tie rods and engaging the outer sides of said flanges to determine the maximum length of said link. The rearward end members 51 are connected with the carriage I 9 by suitable means such as pivots SI and the forsite ends of the shaft An advantage of the yieldable connection (by 4 means of the links 54) is that in the event thatthe blade l5 meets excessive resistance in its forward movement due, for example, to an excessive accumulation of grit or size of bodies in the grit'chamber, the links 54 will yield and the blade will be swung rearwardly to the left hand dot-and-dash position in Fig. 1 and will ride over the material.

When the scraper blade is in effective position, as shown in Fig. 1 in full lines, the bell cranks are in the full line positions with their forwardly extending arms 45 substantially horizontal and their arms 49 substantially vertical with the weights 50 balanced above the rock shaft 46, and the shaft 62 is" slightly below the level of the axis of the pivots 6|. shaft 45 in a counter clockwise direction (Fig. 1), each bell crank 48 assumes the position indicated in dot-and-dasli lines and the scraper I5 is raised and due to the connection of the hangers with the carriage by means of the 1ongitudinally yieldable links 54, is swung forward and assumes the inclined position indicated in dot-and-dash lines at the right of Fig. 1. With the scraper blade in this position the resistance to rearward movement thereof is decreased and the blade will more easily ride over material encountered in its rearward stroke.

It is desirable to raise the scraper blade I5 whenever the'motor is reversed to return the carriage to the left (Fig. 1) and to lower the scraper blade when the motor is reversed to advance the carriage. To this end, the reversing switch 32 is provided with a. suitable operating arm 65 which is so connected, as by means of a-link 66, with an arm 61 fixed on the rock shaft 46, so that rocking of the shaft in one direction will cause the scraper blade to assume its effective position and the motor to be' actuated to advance the blade toward the'pocket l4, and rocking of the shaft in the opposite direction will serve to raise the blade to ineffective position and to actuate the motor to withdraw the scraper blade from the pocket end of the grit chamber.

Automatic actuation of the rock shaft when the carriage reaches the end of its travel may be effected by suitable means such as stops 58 arranged at suitable positions adjacent to the rails 22 and at each end of-the path of travel of the carriage, and arms 69 mounted on oppo- 46 and provided with wheels Hi rotatably mounted thereon in position to engage the upright edges II of said stops. When the bell cranks 43 are positioned as indicated in full lines in Fig. 1, the scraper bar I5 is in its eflective position and the motor 30 is acting to drive the carriage II toward'the outlet end of the grit chamber ID.

When, however, the wheels I9 come into contact with the edges H of the stops 88, the arms 89 will be swung rearwardly and the shaft 48 will be rocked to reverse the motor and at the same time lift the scraper blade l5 and give it a final swing forwardly and upwardly to the right .its path and the shaft inturn is rocked in Upon rocking the v the opposite direction by engagement of the wheels III with corresponding stops at this end, (not shown in the drawings) and thereby effects reversal of the motor and lowering of the scraper blade IS. The carriage with the blade I5 in active position then proceeds again on its travel towards the sump l4 until returned by the said stops 68 as described.

It should be understood that various changes may be made in the construction and arrangement of parts, and that certain parts may be used without others departing from the true spirit and scope of the invention.

I claim: 1. The combination with a grit chamber, of a carriage mounted to travel back and forth along said chamber above the liquid level therein, a scraper carried by said carriage adapted to be immersed in liquid therein and extending across said chamber, means for driving said carriage,

means for reversing. such carriage driving means, and positive means operated by change of direction of said carriage for rendering said scraper alternately operable and inoperable.

2. The combination with a grit chamber, of a carriage mounted to travel back and forth along said chamber, a scraper carried by said carriage and extending across said chamber, means for elevating the scraper, means for driving the carriage, and common controlling. means for the elevating means and the driving means.

3'. The combination with a grit chamber, of a scraper bar extending across said chamber, hangers connected with said scraper bar and extending above the liquid level in said chamber,

a carriage mounted for movement back and forth along said chamber and above said liquid level, means for pivotally supporting saidhangers from said carriage, and yieldable spring means for maintaining the scraper bar in effective position while permitting it to ride over portions of the accumulated solids 'which offer excessive resistance.

4. The combination with a grit chamber, of a carriage mounted travel back and forth along said chamber, a scraper extending across said chamber, means for pivotally raising said scraper, and means for yieldably supporting the scraper against the back pressure of the accumulated material during the effective movement of the scraper, including a longitudinally yieldable link connected at one end with the carriage and at its other end with the scraper.

5. The combination with a grit chamber, of a carriage mounted for movement back and forth along said chamber, a scraper connected with said carriage and extending across said. chamber, carriage-actuating means including a reversible'motor mounted on the carriage, a reversing switch on said carriage and connected I with said motor, means for elevating said scraper, and common controlling means for said switch and such elevating means.

6. The combination with a grit chamber, of a carriage mounted on opposite sides of the grit chamber to travel back and forth along the same, a motor on said carriage for driving the same, contact means; on said carriage and connected with said motor, conducting means parallel to the path of said carriage and engaged by said contact means during the travel of the carriage, a shaft on said carriage, a scraper extending across said chamber, and means including connections between said shaft and said switch and between said shaft and said scraper whereby upon turning the shaft in one direction the scraper will be raised and'the carriage will travel toward the influent end of the chamber, and upon turning the shaft in the other direction the scraper will be lowered and the carriage will travel toward the efiluent end of the chamber.

7. In a settling device the combination of a tank, scraper means in said tank, means for moving the scraper over the bottom of the tank in one direction, leverage mechanism operative when the scraper is moved in the opposite direction for raising the scraper away from the bottom of the tank, and means for removing the settled and scraped substances from the tank.

8. A clarifier for sewage and the like comprising a tank, a carriage movable thereover, sludge scraping means carried by the carriage for scraping sludge from the bottom of the tank, said scraper means being relatively displaceable from a scraping position to a non-scraping position,

leverage mechanism for controlling the position of said-scraper means, and means at each end of the tank for operating said leverage mechanism. 9. A clarifier for sewage and the like compris ing a tank, a carriage movable thereover, sludge scraping means carried by the carriage for scraping sludge from the bottom of the tank and including a blade movable into and out of sludge scraping position, means for moving the carriage alternately in opposite directions over the tank, means for positioning the sludge scraping means in operative and inoperative positions, and stationary means rendered operative by the movement of the carriage for controlling the positioning of said blade.

FRANK A. DOWNES. 

